Automatic choke control



June 10, 1941.

A. w. MESTON' 'AUZOMATIC CHOKE CONTROL Filed Jan. 16, 1932 2Sheets-Sheet 1 rial- INVENTOR Y ALECK w. MESTON av HIS ATTORNEYSPatented June 19, 1941 AU'EGREATK'C CHQZXE GENE RG14 Aleck W. Meston,Toledo, Ohio, assignor to Mote Meter Gauge & Equipment Corporation,Toledo, Ohio, a corporation of Delaware Application January 16, 13-32,Serial No. 587,997

(Cl. res-4.1a)

1d Claims.

This invention relates to automatic choke controls, and moreparticularly to a control mechanism of this character for automaticallycontrolling a choke valve such as is customarily provided for the airirlet pipe of an internal combustion engine.

Objects of the invention are to simplify and improve the constructionand operation of control mechanisms of this character, to render thesame compact and convenient to install, economical to manufacture,reliable in use, not likely to get out of order, and otherwise welladapted for the purpose intended.

Other objects and features of novelty will be apparent as the followingdescription proceeds, reference being had to the accompanying drawings,in which Figure l is an elevation of an internal combustion engineprovided with the automatic choke valve control;

Figure 2 is an enlarged detail section through the air inlet pipe of theengine, taken along the line ?.2 of Figure 4 and showing the details ofth control mechanism;

Figure 3 is a detail elevation of a part of the engine shown in Figure1, showing a modified mounting for the temperature responsive bulb;

Figure 4 is a horizontal section taken along the line 5- of Figure 2,showing th choke control mechanism in plan;

Figure 5 is a section similar to Figure 2, taken along the line 5-5 ofFigure 6, and showing a modified mechanism; and

Figure 6 is a view similar to Figure 4, showing the modified mechanismin plan.

An internal combustion engin it is shown in re 1, and is provided withan inlet manifold H, a carburetor ii, an air inlet pipe l3, and acooling system, which is represented by a water jacket l4 surroundingthe cylinder block of the engine. As shown in Figure 2, the air inletpipe I3 is provided with a choke valve l5 which is of the vane orbutterfly type, being mounted on a shaft 13 which is pivoted in thewalls of the pipe l3.

The choke control mechanism is adapted to open the valve 15 in responseto the suction in the engine inlet manifold ll. Accordingly, a fluidpressure responsive device is mechanically connected to the choke valve15, and pneuma J ically connected to the inlet manifold of the engine,by means of a tube is shown in Figures 1, 2 and 3.

In the form shown, the fluid pressure responsive device comprises acylinder 19 provided with 5;

a piston 28. The piston is provided with a pair of ears 22, betweenwhich is pivoted one end of a link 23, the other end of which is pivotedin a socket 2 3 formed in the blade of the choke valve iii. A spring ismounted in the cylinder [9 under the piston 2b. This spring is seated ina cup the central portion of which is dished inwardly to receive the endof an adjusting screw El, by means of which the compression of thespring may be adjusted.

The automatic control of the choke valve I5 is also responsive to thetemperature of the engine cooling system. The structure for this purposeis best shown in Figure 4. A Bourdon spring is mounted adjacent theinlet air pipe I3, and is connected by means of a capillary tube 32 witha bulb 33, which may be mounted in the water jacket M as shown in Figure1, or may be mounted in a clip 34 secured under the head of one of thecylinder head bolts 35, as shown in Figure 3. The spring 3i), capillarytube 32, and bulb 3 3, as a unit, are filled with an expansible fluid,so that the Bourdon spring is responsive to the temperature of thecooling system. A free end of the spring Bil is connected to an arm 38,which is an extension of the link 23, and thus connects the Bourdo'nspring to the valve l5 for operating the same.

The Bourdon spring 38 is preferably fixed to the side of the air inletpipe at its central portion, thus leaving two free ends 37 and 38, andthe added motion of both ends is applied to open the chok valve. InFigure 4 the free ends are connected by a spring bronze wire 39 whichhas a catenary action. The central'portion of the wire as is received ina slot 4!] formed in the extension arm 35 of the link 23, forming a lostmotion connection.

In Figure 6 a more positiv connection is provided between the Bourdonspring and the valve 5. One end of the link A! is pivoted to the free.nd 87, and one arm of a bell crank 62 is pivoted o the free end 33. Theother end of the link i is pivoted to the intermediate pivot of the bellcrank. The other arm of the bell crank 42 is slotted as at M to receivea lug 45 carried by the extension 3%; of the link 23. The slot 44 iselongated laterally merely to prevent binding of the linkage at thispoint.

The pipe it in. Figure 2 may be a sheet metal extension of thecarburetor air inlet pipe, and a convenient mounting for the Bourdonspring 3%! may be provided by forming a tongue 46 extending from the rimof the pipe, and bending this tongue down over the Bourdon spring. Thesheet metal construction is also of advantage in mounting the cylinderl9. A tongue 41 is struckoutward from the side of the pipe [3, and isturned up as at 48 and apertured to receive the screw 21, the cylinderbeing mounted on the tongue and extending laterally from the pipe. Theforming of the tongue 2| leaves an aperture through which pass theconnections from the piston 20 to the valve [5.

The automatic control mechanism may be mounted within an air cleanercasing which is best shown in Figure 2. This casing comprises a cupmember 50 having a central aperture which is fitted over the pipe l3,and a perforated disk 5|, which is also apertured and fitted over thepipe, and crimped to the rim of the cup as at 51a. The annular space soformed is filled with material which will serve to trap dust and dirtfor cleaning the air supplied to the carburetor, and also to act as aflame arrestor. Bronze wool is a satisfactory material for this purpose.The bottom of the cup 50 is also perforated to permit the air to passtherethrough after having been cleaned by the material in the casing.

A cover member 52 is provided over the open end of the pipe l3 which issurrounded by the cup member 50, and the rim of the cover 52 fits overthe edge of the member 56 and is secured thereto by screws 53. The spacewithin the cover 52 above the cup member 50 and outside of the inlet airpipe l3, contains both the cylinder l9 and the Bourdon spring 3!). Thusthe mechanism is protected from dust, dirt and other conditions, and atthe same time the mechanism is readily accessible for inspection oradjustment.

In operation, assuming that the engine is cold and that the choke valveI5 is closed, when the a suction in the manifold l I, which suction,trans-.

mitted to the cylinder l9, slightly retract the piston and tends to openthe valve 15. This condition, of course. supplies a greater proportionof air to the cylinders of the engine and thus prevents flooding of thecarburetor.

If the engine is very cold, and this opening of the valve supplies toomuch air, so that the engine tends to stall, this condition willdecrease the suction in the manifold II and the cylinder I9, thuspermitting the spring to partially close the valve and thus enrich themixture. When the engine has started and is operating under its ownpower, the valve !5 is maintained open or partly open by the suction asdescribed.

As long as the engine runs smoothly under light load and at relativelyslow speed there is a high vacuum in the intake manifold and the valvestays open or partly open. If, however, the engine fails to run smoothlyor is put under load or accelerated, the vacuum will drop and the valvewill close in a corresponding degree. This operation provides theenrichment of mixture required by a cold motor for pulling or foracceleration. The provision for choking the air supply instead of addingmore fuel to the air fuel mixture as delivered by the carburetor aidsvaporization of the liquid fuel and gives a smoother performance duringthe warm-up period.

The operation of the choke control mechanism is also subject to theaction of the temperature responsive device. When the engine is cold,even after it has been started and is operating under its own power, thecooling system is still cold, and hence the Bourdon spring 3!! may nottend to open the valve [5. As the engine warms up, however, theexpansible fluid in the bulb 33 expands and causes expansion of theBourdon spring. The catenary action of the wire 39 after it reaches theend of the slot 40 tends to further open the valve. In the form shown inFigures 2 and 4, the lost motion afforded by the slot 40 permits openingof the valve by the suction device, without interference from theBourdon spring.

With the form shown in Figs. 5 and 6, the spring 25 is designed to haveless strength, part of the function of the spring being performed by theinherent spring action of the Bourdon spring 30. Thus when the enginehas started, the suction developed in the manifold l I applied to thecylinder It? tends to open the choke valve, but this action is opposedby the Bourdon spring 3!! and the spring 25. However, the spring 25offers so little resistance that the suction is suflicient to overcomethe Bourdon spring and open the valve [5 to the desired extent.

In both forms of the invention, the Bourdon spring is not compensatedfor atmospheric temperature. Hence the operation of the temperatureresponsive device is modified by atmospheric temperature. In otherwords, the Bourdon spring is responsive to a differential temperaturebetween the cylinder head and the surrounding air.

It should be noted that the pivot i5 is off center with respect to thepipe !3. This arrangement causes the engine suction of the air passingthrough the pipe I3 to assist the automatic control in opening thevalve.

While several embodiments of the invention have been disclosed, theinvention is not limited to the details thereof, but instead embracessuch embodiments as fall within the scope of the appended claims.

I claim.

1. In combination with a choke valve associated with the air inlet pipeof an internal combustion engine having a cooling system and an inletmanifold, means responsive to the temperature of said cooling system foropening said valve, a cylinder mounted on said pipe, a piston in saidcylinder, and a bell-crank pivoted on the piston,

one arm being connected to said valve and the other arm to the meansresponsive to temperature, said cylinder being connected to said inletmanifold, whereby said piston is responsive to suction of said manifoldfor opening said valve.

2. In combination with a choke valve associated with the air inlet pipeof an internal combustion engine having a cooling system and an inletmanifold, a Bourdon spring mounted on said air inlet pipe and responsiveto temperature of said cooling system, a cylinder mounted on said pipeand containing a piston responsive to suction of said manifold, and amember connected to said valve and to said piston and having a portionconnected to said'Bourdon spring.

3. In combination with a choke valve associated with the air inlet pipeof an internal combustion engine, having an inlet manifold and a coolingsystem, means responsive to temperature of said cooling system modifiedby atmospheric temperature for opening said choke valve, and a fluidpressure responsive device actuated by said suction in said manifold andconnected to said valve for opening the same.

4. In combination with a choke valve associated with the air inlet pipeof an internal combustion engine having a cooling system and an inletmanifold, an air cleaner casing associated with said air inlet pipe,means responsive to the temperature of said cooling system and a fluidpressure device actuated by suction in said inlet manifold both mountedin said air cleaner casing and both connected to said choke valve foroperating the same.

5. In combination with a choke valve associated with the air inlet pipeof an internal oombustion engine having an inlet manifold, and an aircleaner casing associated with said air inlet pipe, a fluid pressuredevice mounted inside of said air cleaner casing and outside of said airinlet pipe, a tube connecting said fluid pressure device to said inletmanifold, and means connecting said fluid pressure device to said chokevalve for operating the same.

6-. In combination with a choke valve associated with the air inlet pipeof an internal combustion engine having a cooling system, and an aircleaner casing associated with said air inlet pipe, a temperatureresponsive device mounted inside of said air cleaner casing and outsideof said air inlet pipe, a tube connecting said temperature responsivedevice to said cooling systern, and means connecting said temperatureresponsive device to said choke valve for operating the same.

7. In combination with a butterfly choke valve pivoted in the air inletpipe of an internal combustion engine having an inlet manifold, meansfor supporting an annular air cleaner element in position surroundingsaid air inlet pipe, a cover over said air cleaner element and the openend of said pipe, whereby incoming air passes in one direction in anannular path through said air cleaner element and enters said inlet pipein the opposite direction, a fluid pressure device mounted in saidcover, a tube passing through said cover from said fluid pressure deviceto said manifold whereby said device is responsive to suction in saidmanifold, and means actuated by said device and passing through said airinlet pipe for turning said choke valve on its pivot.

8. In combination with a butterfly choke valve pivoted in the air inletpipe of an internal combustion engine having a cooling system, means forsupporting an annular air cleaner element in position surrounding saidair inlet pipe, a cover over said air cleaner element and the open endof said pipe, whereby incoming air passes in one direction in an annularpath through said air cleaner element and enters said air inlet pipe inthe opposite direction, a temperature responsive device mounted in saidcover, a tube passing through said cover from said device to saidcooling system for operating said device therefrom, and means actuatedby said device for turning said choke valve on its pivot.

9. In combination with a butterfly choke valve pivoted in the air inletpipe of an internal combustion engine having an inlet manifold and acooling system, a Bourdon tube responsive to temperature of the coolingsystem having one portion rigidly secured to the outside of the airinlet pipe adjacent the end thereof, said Bourdon tube extendingtransversely of the pipe and partially embracing the pipe, fluidpressure means responsive to suction in the manifold of the enginemounted transversely on the pipe to act in a line parallel to the lineof action of the Bourdon tube, and a member connected to the valve andthe fluid pressure means, and having a portion connected to an end ofthe Bourdon tube whereby the valve is positioned in response to theaction of the Bourdon tube and the fluid pressure means.

10. In a device of the class described, an air inlet pipe of an internalcombustion engine, a choke valve unsymmetrically pivoted in the inletpipe, a Bourdon tube attached adjacent the end of the pipe having twoarms extending symmetrically about the pipe transversely thereof, fluidpressure means mounted transversely of the pipe in a plane between theplane of the Bourdon tube and a transverse plane of the tube runningthrough the pivotal point of the valve, a bell-crank pivoted in theplane of the fluid pressure means and extending on one end into theplane of the Bourdon tube and attached at the other end to the valve ata point displaced from the pivotal point of the valve, means cooperatingwith the bell-crank and the ends of the Bourdon tube in the plane of theBourdon tube, and means establishing a relation between the pivotalpoint of the bell-crank and the fluid pressure means, whereby the chokevalve is positioned'at a point bearing a relation to the position of theBourdon tube and the position of the fluid pressure means.

{ ALECK W. MESTON.

